My impression has always been that Extollager's cats tend to sneak partially into shot inadvertently, as opposed to necessarily being encouraged to take part - but I'm sure Extollager can provide the precise circumstances. Our family cat is above such trivialities as 'paying attention to humans' and would be unlikely to ever sneak into shot - more's the pity, as I like the juxtaposition too.
No, not Bok, but a life-long fan of his, Ronald Clyne. Here's an interesting article about him: eFanzines.com - Earl Kemp: e*I* Vol. 7 No. 6. Scroll down a ways and you'll see A Labor Of Love: The Fantasy Art Of Ronald Clyne. Interesting. The influence of Bok is apparent.Is that a Bok cover?